Vanadyl cyanide

Vanadyl Cyanide.—Berzelius5 obtained vanadyl cyanide by the action of hydrocyanic acid on hydrated hypovanadic oxide in the absence of air. The product was not, however, analysed. 

An unstable double salt of potassium pyrovanadate and potassium cyanide, K4V207.4KCN.14H20, has been prepared,8 as well as a complex addition compound of sodium vanadyl cyanide and hexamethylenetetramine, Na3V0(CN)6.2C8H12N4.5Ha0.9... 

In Table 5 the values for the free standard enthalpies for the reactions of neutral donors and anion donors with vanadyl acetylacetonate are listed. It can be seen that towards the reference molecule iodide ion is a somewhat weaker ligand than propanediol carbonate, whereas the bromide ion is between tri-methylphosphate and acetone, and the chloride ion between DMF and DMSO 22>. The fluoride ion and the NCS -ion are stronger donors than all neutral donors but are somewhat weaker than the azide and the cyanide ion. 

Vanadium tetrachloride, 332—333 Vanadyl acetylacetonate, 331 Vilsmeier reaction, 128 Vilsmeier reagents, 16, 321 Vinyl cyanides, 212 4-Vinylcyclohexene, 25, 209 Vinyl fluorides, 146 Vinyl halides, 186, 212-213 Vinylsilanes, 187... 

DMSO)3VOCl2] + DMSO [(DMSO)4VOCl]+ + Gilt is expected that vanadyl bromide will completely ionize in dimethylsulph-oxide or tributylphosphate, but the situation may be different for fluorides because the fluoride ion has stronger donor properties than bromide or chloride ions towards class (a) metals. Ionization of cyanides and thiocyanates of class (a) metals is unlikely in solvents of donor number below 25 iodides and bromides of class (a) metal ions are completely ionized in solvents of high donor numbers, whilst iodides and bromides of class (b) metals are not ionized in the same media. 

Isomerization of Allylic Alcohols and Formation of 1-Halo-1-alkynes. Isomerization of primary and secondary allylic alcohols to tertiary isomers proceeds in CH2CI2 at 25 °C in the presence of a catalyst that is prepared in situ by activation of vanadyl bis(acetylacetonate) or Mo02(acac)2 with (1) (eq 3). On the other hand, terminal alkynes react with (1) in the presence of copper or zinc halides in THF at —15 °C to afford terminal 1-halo-1-alkynes in 40-85% yields. By the same method, 1-cyano-l-alkynes are obtained in 65% yield by use of copper cyanide. 

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